Transmission for a motor vehicle, motor vehicle powertrain, and method for operating a transmission

ABSTRACT

A transmission (G) for a motor vehicle includes an electric machine (EM1), a first input shaft (GW1), a second input shaft (GW2), an output shaft (GWA), two planetary gear sets (P1, P2, P3), and at least five shift elements (A, B, C, D, E). Different gears are implementable by selectively actuating the at least five shift elements (A, B, C, D, E) and, in addition, in interaction with the electric machine (EM1), different operating modes are implementable. A drive train for a motor vehicle with the transmission (G), and to a method for operating the transmission (G) are also provided.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is related and has right of priority to GermanPatent Application No. 102018215237.3 filed in the German Patent Officeon Sep. 7, 2018 and is a nationalization of PCT/EP2019/071000 filed inthe European Patent Office on Aug. 5, 2019, both of which areincorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The invention relates generally to a transmission for a motor vehicle,including an electric machine, a first input shaft, a second inputshaft, an output shaft, and a first planetary gear set, a secondplanetary gear set, and a third planetary gear set. The planetary gearsets each include multiple elements, wherein a first, a second, a third,a fourth, and a fifth shift element are provided. A rotor of theelectric machine is connected to the second input shaft. Moreover, theinvention relates generally to a motor vehicle drive train, in which thetransmission is utilized, and to a method for operating thetransmission.

BACKGROUND

In hybrid vehicles, transmissions are known which also include, inaddition to a gear set, one or multiple electric machine(s). In thiscase, the transmission is usually configured to be multi-stage, i.e.,multiple different ratios are selectable, as gears, between an inputshaft and an output shaft by actuating appropriate shift elements,wherein this is preferably automatically carried out. Depending on thearrangement of the shift elements, the shift elements are clutches orbrakes. The transmission is utilized in this case for suitablyimplementing an available tractive force of a prime mover of the motorvehicle with respect to various criteria. In this case, the gears of thetransmission are mostly also utilized in interaction with the at leastone electric machine for implementing purely electric driving.Frequently, the at least one electric machine can also be integrated inthe transmission in order to implement various operating modes indifferent ways.

DE 10 2014 218 610 A1 describes a transmission for a hybrid vehicle,which includes, in addition to a first input shaft and an output shaft,three planetary gear sets and an electric machine. Moreover, in onevariant, six shift elements are provided, via which different powerpaths are achieved from the first input shaft to the output shaft whileimplementing different gears and, in addition, different integrations ofthe electric machine can be configured. Here, purely electric drivingcan also be implemented simply by transmitting power via the electricmachine.

SUMMARY OF THE INVENTION

Example aspects of the present invention provide a transmission for amotor vehicle, with which, with a compact design, different operatingmodes can be implemented in a suitable way.

According to example aspects of the invention, a transmission includesan electric machine, a first input shaft, a second input shaft, anoutput shaft, as well as a first planetary gear set and a secondplanetary gear set. The planetary gear sets include multiple elements,wherein, preferably, a first element, a second element, and a thirdelement are associated with each of the planetary gear sets. Inaddition, a first shift element, a second shift element, a third shiftelement, a fourth shift element, and a fifth shift element are provided,via the selective actuation of which different power paths can beimplemented while shifting different gears. It is particularly preferredwhen at least four different gears can be formed between the first inputshaft and the output shaft that differ in terms of ratio. Moreover, arotor of the electric machine is connected to the second input shaft.

Within the meaning of the invention, a “shaft” is understood to be arotatable component of the transmission, via which associated componentsof the transmission are rotationally fixed to each other or via which aconnection of this type is established upon actuation of an appropriateshift element. The particular shaft can connect the components to eachother axially or radially or also both axially and radially. Theparticular shaft can also be present as an intermediate piece, via whicha particular component is connected, for example, radially.

Within the meaning of the invention, “axially” means an orientation inthe direction of a longitudinal central axis, along which the planetarygear sets are arranged coaxially to one another. “Radially” is thenunderstood to mean an orientation in the direction of the diameter of ashaft that lies on this longitudinal central axis.

Preferably, the output shaft of the transmission includes a toothsystem, via which the output shaft is then operatively connected, in themotor vehicle drive train, to a differential gear arranged axiallyparallel to the output shaft. In this case, the tooth system ispreferably provided at a mounting interface of the output shaft, whereinthis mounting interface of the output shaft is preferably situatedaxially in the area of an end of the transmission, at which a mountinginterface of the first input shaft is also provided, the mountinginterface establishing the connection to the upstream prime mover. Thistype of arrangement is particularly suitable for the application in amotor vehicle with a drive train aligned transversely to the directionof travel of the motor vehicle.

Alternatively, an output of the transmission can also be provided, inprinciple, at an axial end of the transmission situated opposite to amounting interface of the first input shaft. In this case, a mountinginterface of the output shaft is then designed at an axial end of theoutput shaft coaxially to a mounting interface of the first input shaft,so that the input and the output of the transmission are located atopposite axial ends of the transmission. A transmission configured inthis way is suitable for the application in a motor vehicle with a drivetrain aligned in the direction of travel of the motor vehicle.

The planetary gear sets are preferably arranged in the sequence firstplanetary gear set, second planetary gear set, and, finally, thirdplanetary gear set axially following the mounting interface of the firstinput shaft. In example aspects, an alternative arrangement of theplanetary gear sets can also be implemented in the axial direction,provided the connection of the elements of the planetary gear setsallows this.

Advantageously, the output shaft is rotationally fixed to the secondelement of the second planetary gear set and rotationally fixable to thefirst input shaft by the second shift element and connectable to thethird element of the first planetary gear set by the fifth shiftelement.

In addition, the first element of the first planetary gear set is fixedat a rotationally fixed component. In addition, the first element of thesecond planetary gear set is fixable at the rotationally fixed componentby the first shift element. In addition, the second input shaft isrotationally fixed to a second element of the first planetary gear setas well as to a third element of the second planetary gear set.

In addition, the first input shaft is rotationally fixable to the secondelement of the first planetary gear set by the third shift element andconnectable in a rotationally fixed manner to the third element of thefirst planetary gear set via the fourth shift element.

By engaging the first shift element, therefore, the first element of thesecond planetary gear set is fixed at a rotationally fixed component. Byengaging the second shift element, the first input shaft is rotationallyfixed to the second element of the second planetary gear set and,thereby, to the output shaft, while an actuation of the third shiftelement results in a rotationally fixed connection between the secondelement of the first planetary gear set and the first input shaft. Thefourth shift element, in the actuated condition, connects the thirdelement of the first planetary gear set and the first input shaft toeach other in a rotationally fixed manner, whereas an engagement of thefifth shift element results in a rotationally fixed connection of thesecond element of the second planetary gear set and the third element ofthe first planetary gear set.

The second shift element, the third shift element, the fourth shiftelement, and the fifth shift element can be clutches, which, uponactuation, each synchronize, if necessary, the particular components ofthe transmission joined directly to the clutches, with respect toturning motions of the particular components and, thereafter, connectthe components to each other in a rotationally fixed manner.

The first shift element can be, in particular, a brake, which, uponactuation, fixes the first element of the second planetary gear set and,consequently, prevents a turning motion thereof.

A particular rotationally fixed connection of the rotatable componentsof the transmission is preferably implemented, according to exampleaspects of the invention, via one or also multiple intermediateshaft(s), which can also be present, in this case, as short intermediatepieces when the components are positioned in a spatially dense manner.Specifically, the components that are permanently rotationally fixed toeach other can each be present either as individual components that arerotationally fixed to each other, or also as single pieces. In thesecond case mentioned above, the particular components and theoptionally present shaft are then formed by one common component,wherein this is implemented, in particular, for the case in which theparticular components are situated spatially close to one another in thetransmission.

In the case of components of the transmission that are rotationallyfixed to each other only upon actuation of a particular shift element, aconnection is also preferably implemented via one or also multipleintermediate shaft(s).

A fixation takes place, in particular, by way of a rotationally fixedconnection to a rotationally fixed component of the transmission, whichis preferably a permanently non-rotating component, preferably a housingof the transmission, a part of such a housing, or a componentrotationally fixed thereto.

Within the meaning of the invention, the “connection” of the rotor ofthe electric machine to the second input shaft of the transmission is tobe understood as a connection of such a type that a constantrotational-speed dependence prevails between the rotor of the electricmachine and the second input shaft.

Overall, a transmission according to example aspects of the invention isdistinguished by a compact design, low component loads, good gearingefficiency, and low losses.

According to one example embodiment of the invention, selectiveengagement of the five shift elements results in four gears between thefirst input shaft and the output shaft that differ in terms of ratio. Afirst gear can be implemented between the first input shaft and theoutput shaft by actuating the first shift element and the fourth shiftelement, in which travel takes place with the simultaneous integrationof a prime mover joined at the first input shaft, and the electricmachine. Moreover, a second gear results between the first input shaftand the output shaft by engaging the first shift element and the thirdshift element. In the process, travel is also implemented in each casewith the simultaneous integration of the upstream prime mover and theelectric machine.

In addition, a third gear can be implemented between the first inputshaft and the output shaft by engaging the first shift element and thesecond shift element. In addition, the third gear can also be selected,in a second variant, by actuating the second and the fifth shiftelements, in a third variant by engaging the fourth and the fifth shiftelements, in a fourth variant by engaging the second and the third shiftelements, and in a fifth variant by engaging the second and the fourthshift elements.

A third gear also results in one further example variant by engaging thesecond shift element. This is the case because the third gear resultsalready by engaging the second shift element, since the first inputshaft and the output shaft are then coupled to one another via the firstplanetary gear set in combination with a rotationally fixed connectionof the output shaft with the second element of the first planetary gearset, so that travel can take place via the upstream prime mover. Theelectric machine can also be decoupled, since, in this case, only thesecond shift element is loaded with torque and, in addition, the secondinput shaft can remain idle. As a result, zero-load losses of theelectric machine can be avoided. However, a shift into the first fivevariants of the third gear has the advantage that the electric machineis also integrated and, as a result, hybrid driving can take place.

A fourth gear can also result between the first input shaft and theoutput shaft by actuating the third shift element and the fifth shiftelement.

Given a suitable selection of stationary transmission ratios of theplanetary gear sets, a transmission ratio range which is suitable forthe application in a motor vehicle is implemented as a result. In thiscase, gear shifts between the gears are implementable, in which only thecondition of two shift elements, in each case, is always to be varied,in that one of the shift elements contributing to the preceding gear isto be disengaged and another shift element is to be engaged in order toimplement the subsequent gear. As a further consequence thereof, a shiftbetween the gears can take place very rapidly.

Due to the connection of the electric machine to the second input shaftof the transmission, different operating modes can also be achieved in asimple way.

A first gear between the second input shaft and the output shaft can beutilized for purely electric driving, wherein this first gear results byengaging the first shift element. As a result, given a rotationallyfixed connection of the output shaft with the second element of thesecond planetary gear set, the rotor of the electric machine is coupled,via the first planetary gear set, with the second planetary gear setand, thereby, with the output shaft. A ratio of this first gearcorresponds to a ratio of the second gear that is effective between thefirst input shaft and the output shaft.

In addition, a second gear can also be implemented between the secondinput shaft and the output shaft for purely electric driving. The fifthshift element is to be actuated in order to engage this second gear. Asa result, given a rotationally fixed connection of the output shaft alsowith the second element of the second planetary gear set, the rotor ofthe electric machine is coupled, via the first planetary gear set, withthe second planetary gear set and, thereby, with the output shaft. Aratio of this second gear, which is effective between the second inputshaft and the output shaft, corresponds to a ratio of the fourth gearbetween the first input shaft and the output shaft.

Starting from purely electric driving in the first gear, which iseffective between the second input shaft and the output shaft, theupstream prime mover can then be started in the first gear, which iseffective between the first input shaft and the output shaft, in thesecond gear, which is effective between the first input shaft and theoutput shaft, and into the first variant of the third gear, which iseffective between the first input shaft and the output shaft, since thefirst shift element contributes to each of these.

A start of the upstream prime mover into the second variant or into thethird variant of the third gear, which is effective between the firstinput shaft and the output shaft, and into the fourth gear, which iseffective between the first input shaft and the output shaft, can alsotake place from the second gear, which is effective between the secondinput shaft and the output shaft.

As a further operating mode, a charging operation of an electricaccumulator can also be implemented, in that only the third shiftelement is engaged and, thereby, a rotationally fixed connection betweenthe first input shaft and the second input shaft and, thereby, also acoupling with the electric machine are established. At the same time, aforce-fit connection to the output shaft is not established, andtherefore the transmission is in a neutral position. Apart from acharging operation, a start of the upstream prime mover via the electricmachine can also be implemented as a result.

Moreover, powershifts with tractive force support can be implemented.During the gearchange between the first gear, which is effective betweenthe first input shaft and the output shaft, and the second gear, whichis effective between the first input shaft and the output shaft, thetractive force with the first shift element engaged can be supported viathe electric machine, wherein the synchronization of the shift elementto be engaged takes place via a closed-loop control of the rotationalspeed of the upstream prime mover. Alternatively, however, this can alsotake place by using synchronized shift elements or also by usinganother, separate synchronizing mechanism, such as a transmission brakeor also one further electric machine, which can be operatively connecteddirectly or indirectly to the first input shaft. If one further shiftelement, as a separating clutch, is also provided on the input side ofthe input shaft, the inertial mass of the upstream drive machine can bedecoupled during the synchronization.

A gearchange under load can also take place between the second gear,which is effective between the first input shaft and the output shaft,and the first variant of the third gear, which is effective between thefirst input shaft and the output shaft, with the first shift elementengaged.

In addition, a gearchange under load can take place between the secondvariant of the third gear, which is effective between the first inputshaft and the output shaft, and the fourth gear, which is effectivebetween the first input shaft and the output shaft, with the fifth shiftelement engaged.

The transmission according to example aspects of the invention can alsobe operated in such a way that a rotational-speed reduction of theelectric machine is achieved during driving. It is therefore possible toinitially drive in a hybrid manner in the first variant of the thirdgear, in that the first shift element initially remains engaged eitherafter a gear shift from the second gear into the third gear with torqueassistance from the electric machine or after a start of the prime moverinto the third gear. In order to now reduce a rotational speed of theelectric machine in the first variant of the third gear at higher groundspeeds, however, a changeover can be implemented from the first variantof the third gear into the second variant of the third gear, since therotor of the electric machine has a lower rotational speed here than inthe first variant of the second gear. This changeover takes place whileobtaining the tractive force via the upstream prime mover, with thesecond shift element engaged. Initially, the load-free, first shiftelement is disengaged and, subsequent thereto, the load-free, fifthshift element is engaged, wherein the rotational-speed adaptation takesplace via closed-loop control of the rotational speed of the electricmachine.

A separate shift element is not necessary for decoupling the upstreamprime mover, since, in the second variant of the third gear, which iseffective between the first input shaft and the output shaft, theupstream prime mover can be decoupled by disengaging the second shiftelement.

As a result, the second gear is then implemented, which is effectivebetween the second input shaft and the output shaft.

In addition, in the case of a vehicle that is slowing down, a downshiftfrom the third gear, which is effective between the first input shaftand the output shaft, into the second gear, which is effective betweenthe first input shaft and the output shaft, can be prepared, in that,initially, a changeover takes place from the second variant into thefirst variant of the third gear and, in the process, the tractive forceis obtained via the upstream prime mover, with the second shift elementengaged. In the first variant of the third gear, the first shift elementis engaged, which becomes necessary in order to support the tractiveforce via the electric machine as part of the downshift from the thirdgear into the second gear.

In one further example design option of the invention, a sixth shiftelement is provided, which is arranged and designed for connecting thefirst element of the second planetary gear set to the first input shaftin a rotationally fixed manner. As a result, a forward electrodynamicstarting operation (EDA mode) can be implemented. EDA means that a speedsuperimposition of the rotational speed of the internal combustionengine, the rotational speed of the electric machine, and the rotationalspeed of the transmission output shaft takes place via one or multipleplanetary gear set(s), and so it is possible to pull away from restwhile the internal combustion engine is running. The electric machinesupports a torque in this case. In order to implement the EDA mode, onlythe sixth shift element is engaged, whereby the first element of thesecond planetary gear set is rotationally fixed to the input shaft. Inthis mode, a ratio of the torque of the internal combustion engineresults that is higher than that of the first gear. This means, thismode expands the overall gear ratio of the transmission.

By providing the sixth shift element, two further variants of the thirdgear, which is effective between the first input shaft and the outputshaft, also result. In this way, a sixth variant results by engaging thesecond shift element and the sixth shift element. A seventh variantresults by engaging the third shift element and the sixth shift element.

According to one further example design option of the invention, aseventh shift element is provided, which is arranged and designed forinterlocking the second planetary gear set. If one planetary gear set isinterlocked, the ratio is always one regardless of the number of teeth.In other words, the planetary gear set revolves as a block.

The interlock can take place in that the seventh shift element connects:

-   -   the first element with the second element of the second        planetary gear set;    -   the first element with the third element of the second planetary        gear set; or    -   the second element with the third element of the second        planetary gear set.

If the seventh shift element is actuated, a third gear results betweenthe second input shaft and the output shaft. A ratio of the thirdelectric gear is between the first electric gear and the second electricgear.

It is pointed out here that the seventh shift element has no functionalrelationship at all with the sixth shift element, and so the seventhshift element can be utilized in an above-described transmission with orwithout a sixth shift element.

As one further example design option of the invention, a furtherelectric machine is provided, the rotor of which is connected at thefirst input shaft. Such an example embodiment has the advantage thatfurther driving modes can be achieved as a result. In addition, as aresult, a start of the upstream prime mover can be implementedimmediately, if necessary, if the prime mover is designed as an internalcombustion engine. In addition, the additional electric machine cansupport the upstream prime mover in the synchronization of shiftelements.

According to one further example embodiment of the invention, the firstinput shaft is connectable in a rotationally fixed manner, via an eighthshift element, to a connection shaft, which, in turn, is then preferablycoupled within a motor vehicle drive train to the prime mover connectedupstream from the transmission. The eighth shift element can be, inprinciple, a force-locking or also as a form-locking shift element inthis case, although it is particularly preferred when the eighth shiftelement is a dog clutch. Via the eighth shift element, the upstreamprime mover can therefore also be completely decoupled from thetransmission, so that a purely electric operation is implementable in aproblem-free manner.

By providing the eighth shift element, the third electric gear can alsobe implemented, alternatively, by engaging the second shift element andthe sixth shift element when the eighth shift element simultaneouslydecouples the internal combustion engine from the input shaft. In thiscase, an above-described seventh shift element is not necessary forimplementing the third electric gear.

In one example refinement of the invention, one or multiple shiftelement(s) is/are each implemented as a form-locking shift element. Inthis case, the particular shift element is preferably designed either asa constant-mesh shift element or as a lock-synchronizer mechanism.Form-locking shift elements have the advantage over friction-lockingshift elements that lower drag losses occur in the disengaged condition,and therefore a better efficiency of the transmission can be achieved.In particular, in the transmission according to example aspects of theinvention, all shift elements are implemented as form-locking shiftelements, and therefore the lowest possible drag losses can be achieved.It is preferred when the seventh shift element, which is provided ifnecessary, is also a force-locking shift element. In principle, however,one shift element or multiple shift elements could also be configured asforce-locking shift elements, for example, as lamellar shift elements.

Within the scope of example aspects of the invention, the planetary gearsets can each be a minus planetary gear set, provided it allows for aconnection of the elements, wherein the first element of the particularplanetary gear set is a sun gear, the second element of the particularplanetary gear set is a planet carrier, and the third element of theparticular planetary gear set is a ring gear. A minus planetary gear setis composed, in a way known, in principle, to a person skilled in theart, of the elements sun gear, planet carrier, and ring gear, whereinthe planet carrier, rotatably mounted, guides at least one planet gear,although preferably multiple planet gears, which each individuallyintermesh with the sun gear and with the surrounding ring gear.

Alternatively thereto, one planetary gear set or also multiple planetarygear sets could also be a plus planetary gear set, however, provided itallows for the connection of the particular elements, wherein the firstelement of the particular planetary gear set is then a sun gear, thesecond element of the particular planetary gear set is a ring gear, andthe third element of the particular planetary gear set is a planetcarrier. In a plus planetary gear set as well, the elements sun gear,ring gear, and planet carrier are present, wherein the planet carrierguides at least one planet gear pair, in which one planet gear is meshedwith the internal sun gear and the other planet gear is meshed with thesurrounding ring gear, and the planet gears are intermeshed with eachother.

Where permitted by a connection of the individual elements, a minusplanetary gear set can be converted into a plus planetary gear set,wherein, as compared to the design as a minus planetary gear set, thering gear connection and the planet carrier connection are to beinterchanged, and a stationary transmission ratio is to be increased byone. Conversely, a plus planetary gear set could also be replaced by aminus planetary gear set, provided the connection of the elements of thetransmission enables this. In this case, as compared to the plusplanetary gear set, the ring gear connection and the planet carrierconnection would also need to be interchanged, and a stationarytransmission ratio would need to be reduced by one. Within the scope ofexample aspects of the invention, the three planetary gear sets are eachpreferably designed as a minus planetary gear set, however.

According to one further example embodiment of the invention, the firstshift element and the fifth shift element are combined to form a shiftelement pair, with which one actuating element is associated. The firstshift element, on the one hand, and the fifth shift element, on theother hand, can be actuated from a neutral position via the actuatingelement. This has the advantage that, due to this combination, thenumber of actuating elements can be reduced and, thereby, themanufacturing complexity can also be reduced.

Alternatively or also in addition to the aforementioned examplevariants, the second shift element and the third shift element arecombined to form a shift element pair, with which one actuating elementis associated. The second shift element, on the one hand, and the thirdshift element, on the other hand, can be actuated from a neutralposition via this actuating element. As a result, the manufacturingcomplexity can be reduced, in that, due to the combination of the twoshift elements to form a shift element pair, one actuating unit can beutilized for both shift elements.

Alternatively to the aforementioned example variant, the second shiftelement and the fourth shift element are combined to form a shiftelement pair, with which one actuating element is associated. The secondshift element, on the one hand, and the fourth shift element, on theother hand, can be actuated from a neutral position via this actuatingelement. As a result, the manufacturing complexity can be reduced, inthat, due to the combination of the two shift elements to form a shiftelement pair, one actuating unit can be utilized for both shiftelements.

In addition, alternatively or also in addition to the two aforementionedexample variants, the fourth shift element and the sixth shift elementare combined to form a shift element pair, with which one actuatingelement is associated. The fourth shift element, on the one hand, andthe sixth shift element, on the other hand, can be actuated from aneutral position via this actuating element. As a result of this aswell, the manufacturing complexity can be reduced, since an actuation ofthe two shift elements can therefore take place via one common actuatingunit.

In addition, alternatively or also in addition to the two aforementionedexample variants, the third shift element and the sixth shift elementare combined to form a shift element pair, with which one actuatingelement is associated. The third shift element, on the one hand, and thesixth shift element, on the other hand, can be actuated from a neutralposition via this actuating element. As a result of this as well, themanufacturing complexity can be reduced, since an actuation of the twoshift elements can therefore take place via one common actuating unit.

It is particularly preferred, in the case that six shift elements areprovided, when all three aforementioned shift elements are implemented,and so the six shift elements of the transmission can be actuated viaonly three actuating elements. As a result, a particularly lowmanufacturing complexity can be achieved.

According to one example embodiment of the invention, the rotor of theelectric machine is rotationally fixed to the second input shaft.Alternatively, according to one example design option of the invention,the rotor is connected to the second input shaft via at least one gearstage. The electric machine can be arranged either coaxially to theplanetary gear sets or so as to lie axially offset with respect thereto.In the former case, the rotor of the electric machine can either berotationally fixed directly to the second input shaft or can be coupledthereto via one or also multiple intermediate gear stage(s), wherein thelatter allows for a more favorable configuration of the electric machinewith higher rotational speeds and lower torques. The at least one gearstage can be designed as a spur gear stage and/or as a planetary gearstage in this case. In the case of a coaxial arrangement of the electricmachine, the two planetary gear sets can then also, more preferably, bearranged axially in the area of the electric machine as well as radiallyinternally with respect thereto, so that the axial installation lengthof the transmission can be shortened.

If the electric machine is provided axially offset with respect to theplanetary gear sets, however, a coupling takes place via one or multipleintermediate gear stage(s) and/or a flexible traction drive mechanism.The one or the multiple gear stage(s) can also be implementedindividually, in this case, either as a spur gear stage or as aplanetary gear stage. A flexible traction drive mechanism can be eithera belt drive or a chain drive.

If a further electric machine is also provided, a rotor of this furtherelectric machine can also be either rotationally fixed to the firstinput shaft directly or can be coupled to the first input shaft via atleast one gear stage. The at least one gear stage can be a spur gearstage or a planetary gear stage or also a flexible traction drivemechanism. In addition, the further electric machine can be providedcoaxially or also axially offset with respect to the first input shaftand, thereby, also to the planetary gear sets.

Within the scope of example aspects of the invention, a startingcomponent can be installed upstream from the transmission, for example ahydrodynamic torque converter or a friction clutch. This startingcomponent can then also be an integral part of the transmission and actsto configure a starting process, in that the starting component enablesa slip speed between the prime mover, which is designed, in particular,as an internal combustion engine, and the first input shaft of thetransmission. In this case, one of the shift elements of thetransmission or the separating clutch, which may be present, can also bedesigned as such a starting component, in that it is present as africtional shift element. In addition, a one-way clutch with respect tothe transmission housing or to another shaft can be arranged on eachshaft of the transmission, in principle.

The transmission according to the invention is, in particular, part of amotor vehicle drive train for a hybrid or electric vehicle and is thenarranged between a prime mover of the motor vehicle, which is configuredas an internal combustion engine or as an electric machine, and furthercomponents of the drive train, which are arranged downstream in thedirection of power flow to driving wheels of the motor vehicle. In thiscase, the first input shaft of the transmission is either permanentlycoupled to a crankshaft of the internal combustion engine or to therotor shaft of the electric machine in a rotationally fixed manner orcan be connected thereto via an intermediate separating clutch or astarting component, wherein a torsional vibration damper can also beprovided between an internal combustion engine and the transmission. Onthe output end, the transmission is then preferably coupled, within themotor vehicle drive train, to a differential gear of a drive axle of themotor vehicle, wherein a connection to an interaxle differential canalso be present in this case, however, via which a distribution tomultiple driven axles of the motor vehicle takes place. The differentialgear or the interaxle differential can be arranged with the transmissionin one common housing in this case. A torsional vibration damper, whichis optionally present, can also be integrated into this housing.

Within the meaning of the invention, the expressions that two componentsof the transmission are “connected” or “coupled” or “are connected toeach other” mean a permanent coupling of these components, and thereforesaid components cannot rotate independently of each other. In thatrespect, no shift element is provided between these components, whichcan be elements of the planetary gear sets and/or also shafts and/or arotationally fixed component of the transmission. Instead, theappropriate components are coupled to each other with a constantrotational speed dependence.

However, if a shift element is provided between two components, thesecomponents are not permanently coupled to each other. Instead, acoupling is carried out only by actuating the intermediate shiftelement. In this case, an actuation of the shift element means, withinthe meaning of the invention, that the particular shift element istransferred into an engaged condition and, consequently, synchronizesthe turning motions, if necessary, of the components connected directlythereto. In the case of an example embodiment of the particular shiftelement as a form-locking shift element, the components directlyconnected to each other in a rotationally fixed manner via the shiftelement rotate at the same rotational speed, while, in the case of aforce-locking shift element, speed differences can exist between thecomponents also after an actuation of the same shift element. Thisintentional or also unintentional condition is nevertheless referred to,within the scope of the invention, as a rotationally fixed connection ofthe particular components via the shift element.

The invention is not limited to the specified combination of features ofthe main claim or the claims dependent thereon. In addition, individualfeatures can be combined with one another, provided they arise from theclaims, the description of preferred embodiments of the invention whichfollows, or directly from the drawings. References in the claims to thedrawings via the use of reference signs is not intended to limit thescope of protection of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous example embodiments of the invention, which are explainedin the following, are represented in the drawings. Wherein:

FIG. 1 shows a diagrammatic view of a motor vehicle drive train;

FIGS. 2 through 5 each show a diagrammatic view of a transmission of thetype that can be utilized in the motor vehicle drive train from FIG. 1 ;

FIG. 6 shows an exemplary shift pattern for five shift elements of thetransmissions from FIGS. 2 through 5 ;

FIG. 7 shows an exemplary shift pattern for six shift elements of thetransmissions from FIGS. 2 through 5 ;

FIGS. 8 and 9 each show a diagrammatic view of a transmission of thetype that can also be utilized in the motor vehicle drive train fromFIG. 1 ;

FIG. 10 shows an exemplary shift pattern for a transmission according toFIG. 8 or 9 ;

FIGS. 11 through 16 each show a schematic of a modification of thetransmissions from FIGS. 2 through 5 as well as FIGS. 8 and 9 ;

FIG. 17 shows a section of the transmissions from FIGS. 4 and 9 ; and

FIGS. 18 through 22 show an exemplary actuating unit for a transmission.

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or moreexamples of which are shown in the drawings. Each embodiment is providedby way of explanation of the invention, and not as a limitation of theinvention. For example, features illustrated or described as part of oneembodiment can be combined with another embodiment to yield stillanother embodiment. It is intended that the present invention includethese and other modifications and variations to the embodimentsdescribed herein.

FIG. 1 shows a diagrammatic view of a motor vehicle drive train of ahybrid vehicle, wherein, in the motor vehicle drive train, an internalcombustion engine VKM is connected to a transmission G via anintermediate torsional vibration damper TS. Connected downstream fromthe transmission G, on the output end thereof, is a differential gearAG, via which drive power is distributed to driving wheels DW of a driveaxle of the motor vehicle. The transmission G and the torsionalvibration damper TS are arranged in a common housing of the transmissionG in this case, into which the differential gear AG can then also beintegrated. As is also apparent in FIG. 1 , the internal combustionengine VKM, the torsional vibration damper TS, the transmission G, andalso the differential gear AG are aligned transversely to a direction oftravel of the motor vehicle.

FIG. 2 shows a schematic of the transmission G according to a firstexample embodiment of the invention. As is apparent, the transmission Gincludes a gear set RS and an electric machine EM1, which are botharranged in the housing of the transmission G. The gear set RS includestwo planetary gear sets P1 and P2, wherein each of the planetary gearsets P1 and P2 includes a first element E11 and E12, respectively, asecond element E21 and E22, respectively, and a third element E31 andE32, respectively. The first element E11 and E12 is formed by a sun gearof the planetary gear set P1 and P2, respectively, while the secondelement E21 and E22 of the planetary gear set P1 and P2, respectively,is present as a planet carrier, and the third element E31 and E32 of theplanetary gear set P1 and P2, respectively, is present as a ring gear.

In the present case, the first planetary gear set P1 and the secondplanetary gear set P2 are each therefore present as a minus planetarygear set. The particular planet carrier thereof guides at least oneplanet gear in a rotatably mounted manner; the planet gear is meshedwith the particular radially internal sun gear as well as with theparticular radially surrounding ring gear. It is particularly preferred,however, when multiple planet gears are provided in the case of thefirst planetary gear set P1 and in the case of the second planetary gearset P2.

As is apparent in FIG. 2 , the transmission G includes a total of fiveshift elements in the form of a first shift element A, a second shiftelement B, a third shift element C, a fourth shift element D, and afifth shift element E. The shift elements A, B, C, D, and E are eachdesigned as form-locking shift elements and are preferably present asconstant-mesh shift elements. While the first shift element A is abrake, the remaining shift elements B, C, D, and E are clutches.

The first element E11 of the first planetary gear set P1 is permanentlyfixed at a rotationally fixed component GG, which is the transmissionhousing of the transmission G or a portion of this transmission housing.The second element E22 of the second planetary gear set P2 isrotationally fixed to an output shaft GWA of the transmission G.Jointly, the second element E22 of the second planetary gear set P2 and,thereby, also the output shaft GWA, is connectable in a rotationallyfixed manner to a first input shaft GW1 of the transmission G byengaging the second shift element B and connectable in a rotationallyfixed manner to the third element E31 of the first planetary gear set P1by engaging the fifth shift element E.

As is also apparent in FIG. 2 , the first input shaft GW1 is connectablein a rotationally fixed manner to the second element E21 of the firstplanetary gear set P1 via the third shift element C. A second inputshaft GW2 of the transmission G is permanently rotationally fixed to thesecond element E21 of the first planetary gear set P1 and to a rotor R1of an electric machine EM1, the stator S1 of which is continuously fixedat the rotationally fixed component GG. Since the rotor R1 is connectedto the second input shaft GW2 and the second input shaft GW2 isrotationally fixed to the second element E21, a connection of the inputshaft GW1 to the second input shaft GW2 takes place simultaneously byengaging the third shift element C.

By actuating the second shift element B, the input shaft GW1 isconnectable to the second element E22 of the second planetary gear setP2 and, thereby, to the output shaft GWA. By actuating the fourth shiftelement D, the first input shaft GW1 also is connectable in arotationally fixed manner to the third element E31 of the firstplanetary gear set P1.

The first input shaft GW1 as well as the output shaft GWA form amounting interface GW1-A and GWA-A, respectively, wherein the mountinginterface GW1-A in the motor vehicle drive train from FIG. 1 is utilizedfor a connection at the internal combustion engine VKM, while thetransmission G is connected at the mounting interface GWA-A to thedownstream differential gear AG. The mounting interface GW1-A of thefirst input shaft GW1 is formed at an axial end of the transmission G,while the mounting interface GWA-A of the output shaft GWA is situatedin the area of the same axial end and, here, is aligned transversely tothe mounting interface GW1-A of the first input shaft GW1. In addition,the first input shaft GW1, the second input shaft GW2, and the outputshaft GWA are arranged coaxially to one another.

The planetary gear sets P1 and P2 are also situated coaxially to theinput shafts GW1 and GW2 and the output shaft GWA, wherein the planetarygear sets P1 and P2 are arranged in the sequence first planetary gearset P1 and second planetary gear set P2 axially subsequent to themounting interface GW1-A of the first input shaft GW1. Likewise, theelectric machine EM1 is also located coaxially to the planetary gearsets P1 and P2 and, thereby, also to the input shafts GW1 and GW2 and tothe output shaft GWA, wherein the electric machine EM1 is arrangedaxially spaced apart from the first planetary gear set P1 and the secondplanetary gear set P2.

As is also apparent from FIG. 2 , the second shift element B, the thirdshift element C, the fourth shift element D, and the fifth shift elementE are arranged axially between the first planetary gear set P1 and thesecond planetary gear set P2, wherein, in this case, the third shiftelement C is situated axially adjacent to the first planetary gear setP1, followed axially initially by the fourth shift element D and thenthe second shift element B and the fifth shift element E. The fifthshift element E is arranged axially approximately at the level of thefourth shift element D and the second shift element B and radiallyspaced apart therefrom.

The first shift element A is situated axially on a side of the secondplanetary gear set P2 facing away from the first planetary gear set P1.

The first shift element A and the fifth shift element E include a commonactuating element, via which the first shift element A, on the one hand,and the fifth shift element E, on the other hand, can be actuated from aneutral position. In that respect, the first shift element A and thefifth shift element E are combined to form a shift element pair SP1.

The fourth shift element D and the second shift element B are situatedaxially directly next to one another and radially at the same level andare combined to form a shift element pair SP2, in that a commonactuating element is associated with the fourth shift element D and thesecond shift element B, via which the fourth shift element D, on the onehand, and the second shift element B, on the other hand, can be actuatedfrom a neutral position. Alternatively, the shift elements B and C aswell as C and D can be combined to form a shift element pair.

Moreover, FIG. 3 shows a diagrammatic view of a transmission G accordingto a second example design option of the invention, which can also beutilized in the motor vehicle drive train from FIG. 1 . This exampledesign option largely corresponds to the preceding example variantaccording to FIG. 2 , with the difference that the first planetary gearset P1 is now designed as a plus planetary gear set.

As compared to the design as a minus planetary gear set, the particularsecond element E21 is formed by the ring gear and the third element E31is formed by the planet carrier. In addition, the stationarytransmission ratio is increased by one. In the plus planetary gear setP1, the planet carrier guides at least one pair of planet gears in arotatably mounted manner. One planet gear of said pair of planet gearsis meshed with the radially internal sun gear and one planet gear ismeshed with the radially surrounding ring gear, and the planet gearsintermesh with each other. In order to connect the first input shaft GW1at the second input shaft GW2, the fourth shift element D must beactuated in the example embodiment according to FIG. 3 .

As in the example embodiment according to FIG. 2 , the shift elements Aand E are combined to form a shift element pair SP1. In contrast to theexample embodiment according to FIG. 2 , the shift element pair isformed by the shift elements B and C, wherein the other two examplevariants would also be conceivable here.

The example design of the first planetary gear set in the “plus variant”has the advantage that, due to the connection of the rotor R1 at theother shaft, the electric gears now have a shorter ratio, whichincreases the tractive force in the electric mode. In addition, apre-ratio of the electric machine EM1, if present, can be smaller andcan even be omitted, if necessary. Otherwise, the example design optionaccording to FIG. 3 corresponds to the example variant according to FIG.2 , and therefore reference is made to the description thereof.

FIG. 4 shows a schematic of a transmission G according to a thirdexample embodiment of the invention, of the type which can also beutilized in the motor vehicle drive train from FIG. 1 . This exampleembodiment also essentially corresponds to the example variant accordingto FIG. 2 , wherein, in contrast thereto, a sixth shift element F is nowprovided. By actuating the sixth shift element F, the first input shaftGW1 is connected in a rotationally fixed manner to the first element E12of the second planetary gear set P2. The sixth shift element F isprovided axially between the first planetary gear set P1 and the secondplanetary gear set P2.

By adding the sixth shift element F, an EDA mode for the electrodynamicstarting operation forward can be advantageously implemented. With thesixth shift element F engaged, the internal combustion engine VKM isconnected to the first element E12 of the second planetary gear set P2,the rotor R1 is connected to the third element E32 of the secondplanetary gear set P2, while the output shaft GWA is connected to thesecond element E22 of the second planetary gear set P2.

In this preferred example embodiment, the six shift elements arecombined to form shift element pairs as follows.

Shift elements A and B form a first shift element pair SP1.

Shift elements B and D form a second shift element pair SP2.

Shift elements C and F form a third shift element pair SP3.

For the rest, the example embodiment according to FIG. 4 corresponds tothe example variant according to FIG. 2 , and therefore reference ismade to the description thereof. With respect to the actuation of thefour shift elements B, C, D, and F by only two actuators, reference ismade to the example embodiment according to FIGS. 17 through 22 .

FIG. 5 shows a diagrammatic view of a transmission G according to afourth example design option of the invention, which can also beutilized in the motor vehicle drive train from FIG. 1 . This exampledesign option largely corresponds to the example variant according toFIG. 2 , with the difference that a seventh shift element K is provided,which, in the actuated condition, interlocks the second planetary gearset P2. According to the example embodiment according to FIG. 5 , theinterlock of the second planetary gear set P2 takes place by connectingthe first element E12 and the second element E22 in a rotationally fixedmanner.

Not represented, but also conceivable is an interlock by connecting, ina rotationally fixed manner, the first element E12 and the third elementE32 as well as the second element E22 and the third element E32 of thesecond planetary gear set P2.

The seventh shift element K allows for an additional electric gear, inthat the seventh shift element is engaged. The additional electric gearcan also be combined with an example embodiment according to FIG. 3(plus gear set variant) and with the example embodiment according toFIG. 4 (EDA mode forward). For the rest, the example embodimentaccording to FIG. 4 corresponds to the example variant according to FIG.2 , and therefore reference is made to the description thereof.

FIG. 6 shows an exemplary shift pattern for the transmissions G fromFIGS. 2 through 5 in table form. As is apparent, a total of four gears 1through 4, which differ in terms of the ratio, are implementable betweenthe first input shaft GW1 and the output shaft GWA, wherein, in thecolumns of the shift pattern, an X indicates which of the shift elementsA through E is engaged in which of the gears 1 through 4.

As is apparent in FIG. 6 , a first gear 1 is engaged between the firstinput shaft GW1 and the output shaft GWA by actuating the first shiftelement A and the fourth shift element D. Moreover, a second gearresults between the first input shaft GW1 and the output shaft GWA byengaging the first shift element A and the third shift element C.

In addition, a third gear can be implemented between the first inputshaft GW1 and the output shaft GWA in a first variant 3.1 by actuatingthe first shift element A and the second shift element B, wherein thethird gear can also be formed in a second variant 3.2 by engaging thesecond shift element B and the fifth shift element E, in a third variant3.3 by actuating the fourth shift element D and the fifth shift elementE, in a fourth variant 3.4 by engaging the second shift element B andthe third shift element C, and in a fifth variant by engaging the secondshift element B and the fourth shift element D. In one further variant(V3), the third gear can be implemented simply by engaging the secondshift element B.

While the electric machine EM1 is also integrated in each of thevariants 3.1 through 3.5, and so driving can take place in a hybridmanner while simultaneously utilizing the internal combustion engine VKMand the electric machine EM1, the electric machine EM1 is decoupled inthe case of the further variant V3. The latter has the advantage thatthe electric machine EM1 does not need to be engaged during operation.

In addition, a fourth gear also results between the first input shaftGW1 and the output shaft GWA by actuating the third shift element C andthe fifth shift element E.

Although the shift elements A through E are each designed as form-fitshift elements, a power shift can be implemented between the first gear1 and the second gear 2, between the first variant 2.1 of the secondgear and the first variant 3.1 of the third gear, and between the secondvariant 3.2 of the third gear and the fourth gear 4. The reason thereforis that the first shift element A contributes to the changeover from thesecond gear 2 into the first variant 3.1 and to the changeover from thefirst variant 3.1 into the second variant 3.2. The shift element Econtributes to the changeover from the second variant 3.2 of the thirdgear to the fourth gear 4. A synchronization during the gear shifts cantake place in each case via an appropriate closed-loop control of theupstream internal combustion engine VKM, and therefore the particularshift element to be disengaged is disengaged without load and the shiftelement to be subsequently engaged can be engaged without load.

The transmissions G from FIGS. 2 through 5 can also be operated inalternative operating modes with the aid of the electric machine EM1.Purely electric driving can take place in a first gear E2, which iseffective between the second input shaft GW2 and the output shaft GWAand, for the implementation of which, the first shift element A is to betransferred into an engaged condition. As a result, with the first shiftelement A engaged, the first electric machine EM1 is directly connectedto the output shaft GWA with a constant ratio (third element E32rotatable with the second element E22 while the first element E12 of thesecond planetary gear set P2 is fixed). The ratio of the first gear E2corresponds here, in each case, to a ratio of the second gear 2 betweenthe first input shaft GW1 and the output shaft GWA.

In addition, a second gear E4 can also be implemented between the secondinput shaft GW2 and the output shaft GWA, for the implementation ofwhich the fifth shift element E is to be engaged. As a result, theelectric machine EM1 is connected to the output shaft GWA with aconstant ratio (second element E21 rotatable with the third element E31while the first element E11 of the first planetary gear set P1 isfixed). A ratio of this second gear E4 corresponds, in each case, to aratio of the fourth gear 4, which is effective between the first inputshaft GW1 and the output shaft GWA.

Advantageously, a start of the internal combustion engine VKM into thefirst gear 1, into the second gear 2, and into the first variant 3.1 ofthe third gear 3 can be carried out starting from the first gear E2,since the first shift element A is engaged in each of these gears. Thesame is possible from the second gear E4 into the second variant 3.2 ofthe third gear, into the third variant 3.3 of the third gear, or intothe fourth gear 4, since the fifth shift element E contributes to eachof these gears. Therefore, a transition from purely electric drivinginto driving via the internal combustion engine or into hybrid drivingcan be carried out rapidly.

Moreover, a charging or starting function can be implemented by engagingthe third shift element C. This is the case because, in the engagedcondition of the third shift element C, the second input shaft GW2 isdirectly coupled, in a rotationally fixed manner, to the first inputshaft GW1 and, thereby, also to the internal combustion engine VKM,wherein, simultaneously, there is no force-fit connection to the outputshaft GWA. When the electric machine EM1 is operated as a generator, anelectric accumulator can be charged via the internal combustion engineVKM, whereas, when the electric machine EM1 is operated as an electricmotor, a start of the internal combustion engine VKM is implementablevia the electric machine EM1.

In addition, a rotational-speed reduction of the electric machine EM1can be configured in the mechanical or hybrid mode. After a gear shiftfrom the second gear into the third gear, with torque support via theelectric machine EM1, or after a start of the internal combustion engineVKM into the third gear, hybrid driving results.

In order to reduce the rotational speed of the electric machine EM inthe third gear at higher ground speeds, a changeover can be carried outfrom the first variant 3.1 of the third gear into the second variant3.2, in which the rotor R1 has a lower rotational speed. This changeovertakes place while obtaining the tractive force via the internalcombustion engine VKM with the second shift element B engaged. For thispurpose, the first shift element A, which is then load-free, isdisengaged and the likewise load-free, fifth shift element E is engaged,wherein the rotational-speed adaptation takes place in each case viaclosed-loop control of the rotational speed of the electric machine EM.

The changeover into the second variant 3.2 also has the advantage thatthe internal combustion engine VKM can be decoupled at any time bydisengaging the second shift element B also in the absence of anadditional separating clutch, while the electric machine EM1 drives ordecelerates the vehicle. Moreover, in the case of a vehicle that isslowing down, a downshift from the third gear into the second gear canbe prepared, in that, initially, a changeover takes place from thesecond variant 3.1 into the first variant 1.1, while the internalcombustion engine VKM maintains the tractive force with the second shiftelement B engaged. In the first variant 3.1 of the third gear, the firstshift element A is engaged, which becomes necessary in order to supportthe tractive force via the electric machine EM during the downshift fromthe third gear into the second gear.

FIG. 7 shows an exemplary shift pattern for the transmissions G fromFIGS. 2 through 5 with a sixth shift element F, in table form. As isapparent, a total of four gears 1 through 4, which differ in terms ofthe ratio, are implementable between the first input shaft GW1 and theoutput shaft GWA, wherein, in the columns of the shift pattern, an Xindicates which of the shift elements A through F is engaged in which ofthe gears 1 through 4.

In contrast to the shift pattern from FIG. 6 , two further variants of athird gear, which is effective between the first input shaft GW1 and theoutput shaft GWA, result due to the sixth shift element F. A sixthvariant 3.6 of the third gear results by actuating the second shiftelement B and the sixth shift element F, whereas a seventh variant 3.7of the third gear results by actuating the third shift element C and thesixth shift element F.

As is also apparent from FIG. 7 , two additional gears Z1 and Z2 areengageable. The additional gear Z1 results by actuating the fourth shiftelement D and the sixth shift element F, whereas the additional gear Z2results by actuating the fifth shift element E and the sixth shiftelement F.

Therefore, a total of four additional hybrid forward gears result due tothe sixth shift element.

Moreover, FIG. 8 shows a schematic of a transmission G according to afifth example embodiment of the invention, of the type which can also beutilized in the motor vehicle drive train from FIG. 1 . This exampleembodiment essentially corresponds to the example variant according toFIG. 2 , wherein, in contrast thereto, the first input shaft GW1 is nowrotationally fixable, at the mounting interface GW1-A via an eighthshift element K0, to a connection shaft AN, which is then connected tothe upstream internal combustion engine VKM in the motor vehicle drivetrain. The seventh shift element K0 is configured as a form-lockingshift element and, particularly preferably, is present as aconstant-mesh shift element. Moreover, a further electric machine EM2 isalso provided, the rotor R2 of which is rotationally fixed to the firstinput shaft GW1, while a stator S2 of the further electric machine EM2is fixed at the rotationally fixed component GG. The rotor R2 isconnected at the first input shaft GW1 axially between the seventh shiftelement K0 and the first planetary gear set P1. For the rest, theexample variant according to FIG. 8 corresponds to the example designoption according to FIG. 2 , and therefore reference is made to thedescription thereof.

FIG. 9 shows a diagrammatic view of a transmission G according to asixth example design option of the invention. This example design optioncan also be utilized in the motor vehicle drive train from FIG. 1 ,wherein the example design option largely corresponds to the examplevariant from FIG. 4 . The difference now, however, is that the firstinput shaft GW1 can be connected, at the mounting interface GW1-A, as isalso the case in the preceding example variant according to FIG. 8 , viaan eighth shift element K0 in a rotationally fixed manner to aconnection shaft AN, which is then connected to the upstream internalcombustion engine VKM in the motor vehicle drive train. In this case,the eighth shift element K0 is designed as a form-locking shift elementand, in this case, preferably as a constant-mesh shift element. Inaddition, a further electric machine EM2 is also provided, the rotor R2of which is rotationally fixed to the first input shaft, while a statorS2 of the further electric machine EM2 is fixed at the rotationallyfixed component GG. A connection of the rotor R2 of the further electricmachine EM2 at the first input shaft GW1 is implemented axially betweenthe eighth shift element K0 and the first planetary gear set P1.Otherwise, the example variant according to FIG. 9 corresponds to theexample embodiment according to FIG. 4 , and therefore reference is madeto the description thereof.

In FIG. 10 , different conditions of the motor vehicle drive train fromFIG. 1 , with utilization of the transmission G from FIG. 8 or 9 , arerepresented in table form, wherein these different conditions areachieved via different integrations of the two electric machines EM1 andEM2 and the internal combustion engine VKM. The column with the sixthshift element F is relevant only for the transmission according to FIG.9 .

First, purely electric driving by a single electric machine anddisengaged shift element K0 is described.

In the first gear E2, purely electric driving takes place via theelectric machine EM1, in that the first gear E2 is implemented in thetransmission G in the way described above with respect to FIG. 6 . Inthe second gear E4, purely electric driving also takes place via theelectric machine EM1, in that the second gear E4 is implemented in thetransmission G in the way described above with respect to FIG. 6 . Inthe third gear E3, purely electric driving takes place via the electricmachine EM2, in that the third gear E3 is implemented in thetransmission G by actuating the second shift element B.

Second, purely electric driving by both electric machines and disengagedshift element K0 is described.

The same gear steps can be implemented as described in FIGS. 5 and 6 ,wherein these can now be driven purely electrically.

Starting at the gear E1, driving then takes place via the electricmachine EM1 and via the second electric machine EM2, in that bothelectric machines EM1 and EM2 are jointly integrated via the selectionof the appropriate gears in the transmission G. A first gear E1 isselected by engaging the shift elements A and D. A second gear E2 isselected by engaging the shift elements A and C. A third gear in a firstvariant E3.1 is selected by engaging the shift elements A and B. Asecond variant E3.2 of the third gear is selected by engaging the shiftelements B and E. A third variant E3.3 of the third gear is selected byengaging the shift elements D and E. By engaging the shift elements Band C, a fourth variant E3.4 of the third gear is selected. A fifthvariant E3.5 of the third gear is selected by engaging the shiftelements B and D. A sixth variant E3.6 of the third gear is selected byengaging the shift elements B and F. A seventh variant E3.7 of the thirdgear is selected by engaging the shift elements C and F. A fourth gearE4 is selected by engaging the shift elements C and E. The additionalforward gear EZ1 is selected by engaging the shift elements D and F. Theadditional forward gear EZ2 is selected by engaging the shift elements Eand F.

With the clutch K0 engaged, the same gears are also implementable asdescribed in FIGS. 6 and 7 .

The advantages of two electric machines can be summarized as follows:

-   -   purely electric powershift, since the second electric machine        EM2, with disengaged shift element K0, performs the functions of        the internal combustion engine;    -   the second electric machine EM2, with disengaged shift element        K0, can be utilized for synchronization, while the first        electric machine EM1 supports the tractive force;    -   a greater total electrical power is implementable with        disengaged shift element K0;    -   a greater range is possible in a hybrid operation;    -   the internal combustion engine VKM can be started by the second        electric machine EM2;    -   the second electric machine EM2 can synchronize the shift        element K0;    -   a battery-independent serial operation is possible; and    -   the second electric machine EM2 can be used as a generator, the        first electric machine EM1 can be used as a motor.

Due to the additional shift element F, as described above, an EDA modefor forward travel can be implemented.

In addition, a purely electric EDA mode can be implemented. As a result,driving can also take place for a longer time with high torque and a lowground speed without the electric machine or the inverter overheating,since both electric machines can be operated at suitable rotationalspeeds. An operation at very low electric-machine rotational speeds isavoided.

In addition, in the purely electric EDA mode, a purely electric gearshift (EDS) is possible (K0 is disengaged while the shift element F isengaged), i.e., the electric gears of the first electric machine EM1 arepower shiftable among one another. It is advantageous here that thefirst electric machine EM1 also contributes the greatest portion of thedrive power during the gear shift, while the second electric machine EM2can therefore be dimensioned considerably smaller (for example, onlyapproximately a third (⅓) the power of EM1).

With the clutch K0 engaged, the same shift conditions are implementableduring hybrid travel and during internal combustion engine-driventravel, as explained with respect to FIGS. 6 and 7 , and so reference ismade to the descriptions thereof.

The electric machines EM1 and EM2 can be positioned either coaxially tothe gear set as well as axially parallel to the input shaft. Theelectric machines can be connected to the particular transmission shaftdirectly or via further gear stages, such as a planetary gear set or aspur gear stage. An additional gear stage can be useful, therefore, inorder to obtain a more favorable design of the particular electricmachine. In this way, for example, a higher rotational speed and a lowertorque can be achieved.

Finally, FIGS. 11 through 16 show modifications of the exampletransmissions G from FIGS. 2 through 5 as well as FIGS. 8 and 9 . Theseexample modifications relate to alternative possibilities forintegrating the electric machine EM1, although the example modificationscan also be utilized, in a similar way, for the further electric machineEM2 in the transmissions G according to FIGS. 8 and 9 .

In FIG. 11 , for example, the electric machine EM1 is not locatedcoaxially to the particular gear set RS (not represented in greaterdetail here) of the transmission G, but rather is arranged axiallyoffset with respect thereto. A connection takes place via a spur gearstage SRS, which is composed of a first spur gear SR1 and a second spurgear SR2. The first spur gear SR1 is connected at the second input shaftGW2 in a rotationally fixed manner on the side of the particular gearset RS. The spur gear SR1 then meshes with the spur gear SR2, which islocated on an input shaft EW of the electric machine EM1 in arotationally fixed manner. Within the electric machine EM1, the inputshaft EW establishes the connection at the rotor (not representedfurther in this case) of the electric machine EM1.

In the case of the example modification according to FIG. 12 as well,the electric machine EM1 is located axially offset with respect to theparticular gear set RS of the particular transmission G. In contrast tothe preceding example variant according to FIG. 11 , a connection is notestablished in this case via a spur gear stage SRS, however, but rathervia a flexible traction drive mechanism ZT. This flexible traction drivemechanism ZT can be configured as a belt drive or also a chain drive.The flexible traction drive mechanism ZT is then connected at the secondinput shaft GW2 on the side of the particular gear set RS. Via theflexible traction drive mechanism ZT, a coupling to an input shaft EW ofthe electric machine EM1 is then established. Within the electricmachine EM1, the input shaft EW establishes a connection at the rotor ofthe electric machine.

In the case of the example modification according to FIG. 13 , anintegration of the electric machine EM1, which is located axially offsetwith respect to the particular gear set RS, is implemented via aplanetary gear stage PS and a spur gear stage SRS. The planetary gearstage PS is connected downstream from the gear set RS, wherein, on theoutput end of the planetary gear stage PS, the spur gear stage SRS isthen provided, via which the connection to the electric machine EM1 isestablished. The planetary gear stage PS includes a ring gear HO, aplanet carrier PT, and a sun gear SO, wherein the planet carrier PTguides, in a rotatably mounted manner, at least one planet gear PR,which is meshed with the sun gear SO as well as with the ring gear HO.

In the present case, the planet carrier PT is connected at the secondinput shaft GW2 in a rotationally fixed manner on the side of the gearset RS from FIGS. 2 through 5 as well as FIGS. 8 and 9 . By comparison,the ring gear HO is permanently fixed at the rotationally fixedcomponent GG, while the sun gear SO is rotationally fixed to a firstspur gear SR1 of the spur gear stage SRS. The first spur gear SR1 thenintermeshes with a second spur gear SR2 of the spur gear stage SRS,which is provided, in a rotationally fixed manner, on an input shaft EWof the electric machine EM1. In this case, the electric machine EM1 istherefore connected by the gear set RS via two gear stages.

In the case of the example modification from FIG. 14 as well, anintegration of the electric machine EM1 is implemented by the gear setRS via a planetary gear stage PS and a spur gear stage SRS. Themodification largely corresponds to the variant according to FIG. 13 ,with the difference that, with respect to the planetary gear stage PS,the sun gear SO is now fixed at the rotationally fixed component GG,while the ring gear HO is rotationally fixed to the first spur gear SR1of the spur gear stage SRS. Specifically, the ring gear HO and the firstspur gear SR1 are preferably designed as one piece, in that the ringgear HO is equipped, at an outer circumference, with a tooth system. Forthe rest, the example modification according to FIG. 14 corresponds tothe example variant according to FIG. 13 , and therefore reference ismade to the description thereof.

Moreover, FIG. 15 shows one further example modification of thetransmissions G from FIGS. 2 through 5 as well as FIGS. 8 and 9 ,wherein, in this case as well, an integration of the electric machineEM1 is implemented via a spur gear stage SRS and a planetary gear stagePS. In contrast to the preceding example variant according to FIG. 14 ,the gear set RS is initially followed here by the spur gear stage SRS,while the planetary gear stage PS is provided in the power flow betweenthe spur gear stage SRS and the electric machine EM1. The planetary gearstage PS also includes, once again, the elements ring gear HO, planetcarrier PT, and sun gear SO, wherein the planet carrier PT guides, in arotatably mounted manner, multiple planet gears PR1 and PR2, each ofwhich is meshed with the sun gear SO as well as with the ring gear HO.

As is apparent in FIG. 15 , a first spur gear SR1 of the spur gear stageSRS is connected in a rotationally fixed manner on the side of the gearstage RS of the transmissions G from FIGS. 2 through 5 as well as FIGS.8 and 9 , wherein this connection is completed at the second input shaftGW2. The first spur gear SR1 then intermeshes with a second spur gearSR2 of the spur gear stage SRS, which is rotationally fixed to theplanet carrier PT of the planetary gear stage PS. The ring gear HO ispermanently fixed at the rotationally fixed component GG, while the sungear SO is provided, in a rotationally fixed manner, on an input shaftEW of the electric machine EM1.

Finally, FIG. 16 shows one further example modification of thetransmission G from FIGS. 2 through 5 as well as FIGS. 8 and 9 , whereinthis example modification essentially corresponds to the precedingexample variant according to FIG. 15 . The only difference is that thesun gear SO of the planetary gear stage PS is now permanently fixed atthe rotationally fixed component GG, while the ring gear HO of theplanetary gear stage PS is rotationally fixed to the input shaft EW ofthe electric machine EM1. For the rest, the example modificationaccording to FIG. 16 corresponds to the example variant according toFIG. 15 , and therefore reference is made to the description thereof.

FIG. 17 shows a section of the four inner shift elements, namely thesecond shift element B, the third shift element C, the fourth shiftelement D, and the sixth shift element F from the transmission accordingto FIGS. 4 and 9 in a simplified diagrammatic view. As is readilyapparent, the four shift elements B, C, D, and F are associated with thesame shaft, namely the first input shaft GW1, wherein the two “outer”shift elements C and F are spatially separated by the shift elements Dand B. The manner in which four shift elements of this type can beactuated by only two actuators is the object of FIGS. 18 through 22 .

FIGS. 18 through 22 each show a schematic of an actuating unit 10 of thetype which can be utilized, for example, for actuating the second shiftelement B, the third shift element C, the fourth shift element D, andthe sixth shift element F. The shift elements B, C, D, and F can beactuated from the “inside” out, i.e., from the inside of the input shaftGW1. The four shift elements B, C, D, and F are actuated by twoactuating elements designed as control rods S1, S2, which, in turn, areeach actuated by an actuator A1, A2, respectively. The actuation of theshift elements B, C, D, and F takes place from within the input shaft,i.e., from the inside. The shift elements B, C, D, and F areconstant-mesh shift elements.

With respect to FIG. 18 , the input shaft GW1 of the transmission G isdesigned as a hollow shaft in this case. A first control rod S1 is alsodesigned as a hollow shaft, whereas a second control rod S2 is designedas a solid shaft. Both control rods S1, S2 are guided within the inputshaft GW1, wherein the second control rod S2 is guided within the firstcontrol rod S1. As viewed radially from the outside, the sequenceresults: input shaft GW1, first control rod S1, second control rod S2.The first control rod S1 can be actuated by a first actuator A1, whereasthe second control rod S2 can be actuated by a second actuator A2.

The actuators A1, A2 are arranged on a side of the sixth shift element Ffacing away from the third shift element C.

In the actuated, i.e., engaged condition, the shift elements C, D, B,and F rotationally fix the input shaft GW1 to another shaft in eachcase. In this way,

-   -   the third shift element C connects the input shaft GW1 to a        second shaft 22,    -   the fourth shift element D connects the input shaft GW1 to a        third shaft 33,    -   the second shift element B connects the input shaft GW1 to a        fourth shaft 44, and    -   the sixth shift element F connects the input shaft GW1 to a        fifth shaft 55.

The second shaft 22 can form at least one portion of the second inputshaft GW2 or of the second element E21 of the first planetary gear setP1 or be connected thereto. The fourth shaft 44 can form at least aportion of the third element E31 of the first planetary gear set P1 orbe connected thereto. The fifth shaft 55 can form at least a portion ofthe second element E22 of the second planetary gear set P2 or beconnected thereto. The third shaft 33 can form at least a portion of thefirst element E12 of the second planetary gear set P2 or be connectedthereto.

For the form-fitting connections, the shafts 22, 33, 44, and 55 includetooth systems 2 a, 3 a, 4 a, and 5 a, respectively, which correspond totooth systems 2 b, 3 b, 4 b, and 5 b, respectively, of the dogs. Themode of operation of dog clutches is known from the prior art, and so itwill not be discussed in greater detail here.

Each control rod S1, S2 can actuate precisely two shift elements. As isto be easily derived from FIG. 17 , the first control rod S1 actuatesthe second shift element B and the fourth shift element D, which aredesigned as a double shift element in the present case. The secondcontrol rod S2, however, actuates the shift elements C, F spatiallyseparated from one another.

In order to actuate the fourth shift element D, the first actuator A1,starting from a non-actuated condition, moves the first gear change rodS1 in the arrow direction 98, i.e., toward the left in the viewingdirection. In order to actuate the second shift element B, the firstactuator A1, starting from a non-actuated condition, moves the firstgear change rod S1 in the arrow direction 99, i.e., toward the right inthe viewing direction.

In order to actuate the third shift element C, the second actuator A2,starting from a non-actuated condition, moves the second gear change rodS2 in the arrow direction 96, i.e., toward the left in the viewingdirection. In order to actuate the sixth shift element F, the secondactuator A2, starting from a non-actuated condition, moves the secondgear change rod S2 in the arrow direction 97, i.e., toward the right inthe viewing direction.

In order to ensure that the shift elements can be actuated from withinthe input shaft GW1, the input shaft GW1 includes three recesses, namelya first recess 11, a second recess 12, and a third recess 13. Inaddition, the first control rod S1 includes a recess 21. The recessesare oblong holes in the present case.

A mechanical coupling or connection of the third shift element C withthe second control rod S2 takes place through the first oblong hole 11of the input shaft GW1. A mechanical coupling of the shift elements B, Dwith the first control rod S1 takes place through the second oblong hole12 of the input shaft GW1. Due to the design as a double shift element,the mechanical connection of two shift elements is possible through onlyone oblong hole. The mechanical coupling of the sixth shift element F,however, takes place through the two mutually corresponding, i.e.,essentially aligned oblong holes 13, 21 of the input shaft GW1 and thefirst control rod S1, respectively.

The particular shift element C, D, B, and F is rotationally fixed to thecontrol rod S1, S2 via a section (not described in greater detail),which is guided through the particular oblong hole 11, 12, 13, and 21.

The shift elements C and F, on the one hand, and D and B, on the otherhand, are collectively controlled. This means, when the third shiftelement C is engaged, the sixth shift element F is simultaneouslydisengaged, and vice versa. The same also applies for the shift elementsC and D.

In order to ensure that the one control rod does not inadvertently movethe other control rod and, thereby, possibly engage or disengage a shiftelement, the oblong hole 21 of the first control rod S1 has a largerdiameter than the third oblong hole 13 of the input shaft GW1. In thepresent case, the diameter is twice as great. As is also apparent, thetwo control rods are aligned with respect to one another in such a waythat the two oblong holes 13, 21 are aligned with one another when theshift elements are each in a non-actuated condition.

By the actuating unit 10, the two shift elements C, F arranged on theoutside can be actuated by only one gear change rod and by only oneactuator. Therefore, only two actuators A1, A2 are necessary for thefour shift elements C, D, B, and F.

FIG. 19 shows a schematic of the actuating unit 10 in a second exampleembodiment. In contrast to the example embodiment according to FIG. 17 ,the first control rod S1 actuates the two shift elements C and F. Theshift elements D and B are actuated by the second control rod S2,however. For this purpose, the oblong hole 21 is arranged in the firstcontrol rod S1 in such a way that the oblong hole 21 corresponds to thesecond oblong hole 12 of the input shaft GW1. The oblong holes 11, 12,13 remain unchanged.

In order to actuate the shift element D, the second actuator A2,starting from a non-actuated condition, therefore moves the second gearchange rod S2 in the arrow direction 98, i.e., toward the left in theviewing direction. In order to actuate the shift element B, the secondactuator A2, starting from a non-actuated condition, moves the secondgear change rod S2 in the arrow direction 99, i.e., toward the right inthe viewing direction.

In order to actuate the shift element C, the first actuator A1, startingfrom a non-actuated condition, moves the first gear change rod S1 in thearrow direction 96, i.e., toward the left in the viewing direction. Inorder to actuate the shift element F, the first actuator A1, startingfrom a non-actuated condition, moves the first gear change rod S1 in thearrow direction 97, i.e., toward the right in the viewing direction. Forthe rest, the example variant according to FIG. 19 corresponds to theexample embodiment according to FIG. 18 , and therefore reference ismade to the description thereof.

FIG. 20 shows a schematic of the actuating unit 10 in a third exampleembodiment. In contrast to the example embodiment according to FIG. 19 ,the second control rod S2 is designed as a hollow shaft. This allows fora lighter weight and offers space for an oil lubrication (notrepresented in the present case). For the rest, the example variantaccording to FIG. 20 corresponds to the example embodiment according toFIG. 18 , and therefore reference is made to the description thereof.

FIG. 21 shows a schematic of the actuating unit 10 in one furtherexample embodiment. In contrast to the example embodiment according toFIG. 18 , the shift elements D and B are each designed as a single shiftelement. This makes a fourth oblong hole 14 in the input shaft GW1necessary. The fourth oblong hole 14 is arranged axially between thesecond oblong hole 12 and the third oblong hole 13.

In contrast to the example embodiment according to FIG. 18 , the fourthoblong hole 14 of the input shaft GW1 now corresponds to the oblong hole21 of the first control rod S1. In this way, four spatially separatedshift elements, namely A and D, on the one hand, and C and D, on theother hand, can be actuated by precisely two actuators A1, A2. For therest, the example variant according to FIG. 21 corresponds to theexample embodiment according to FIG. 18 , and therefore reference ismade to the description thereof.

FIG. 22 shows a schematic of the actuating unit 10 in one furtherexample embodiment. In contrast to the example embodiment according toFIG. 18 , the shift elements D and B are each designed as a single shiftelement. This makes a fourth oblong hole 14 in the input shaft GW1necessary. The fourth oblong hole 14 is arranged axially between thesecond oblong hole 12 and the third oblong hole 13. As in FIG. 17 , theoblong hole 21 of the first control rod S1 corresponds to the thirdoblong hole 13 of the input shaft GW1.

As in the example embodiment according to FIG. 18 , the first controlrod S1 actuates the shift elements D and B, whereas the second controlrod S2 actuates the shift elements C and F. For the rest, the examplevariant according to FIG. 22 corresponds to the example embodimentaccording to FIG. 18 , and therefore reference is made to thedescription thereof.

Using example embodiments of the invention, a transmission having acompact design and good efficiency can be implemented.

Modifications and variations can be made to the embodiments illustratedor described herein without departing from the scope and spirit of theinvention as set forth in the appended claims. In the claims, referencecharacters corresponding to elements recited in the detailed descriptionand the drawings may be recited. Such reference characters are enclosedwithin parentheses and are provided as an aid for reference to exampleembodiments described in the detailed description and the drawings. Suchreference characters are provided for convenience only and have noeffect on the scope of the claims. In particular, such referencecharacters are not intended to limit the claims to the particularexample embodiments described in the detailed description and thedrawings.

REFERENCE CHARACTERS

G transmission

RS gear set

GG rotationally fixed component

P1 first planetary gear set

E11 first element of the first planetary gear set

E21 second element of the first planetary gear set

E31 third element of the first planetary gear set

P2 second planetary gear set

E12 first element of the second planetary gear set

E22 second element of the second planetary gear set

E32 third element of the second planetary gear set

A first shift element

B second shift element

C third shift element

D fourth shift element

E fifth shift element

F sixth shift element

K seventh shift element

K0 eighth shift element

SP1 shift element pair

SP2 shift element pair

SP3 shift element pair

1 first gear

2 second gear

3.1 third gear

3.2 third gear

3.3 third gear

3.4 third gear

3.5 third gear

3.6 third gear

3.7 third gear

4 fourth gear

E2 first gear

E4 second gear

E3 third gear

V3 third gear

GW1 first input shaft

GW1-A mounting interface

GW2 second input shaft

GWA output shaft

GWA-A mounting interface

AN connection shaft

EM1 electric machine

S1 stator

R1 rotor

EM2 electric machine

S2 stator

R2 rotor

SRS spur gear stage

SR1 spur gear

SR2 spur gear

PS planetary gear stage

HO ring gear

PT planet carrier

PR planet gear

PR1 planet gear

PR2 planet gear

SO sun gear

ZT flexible traction drive mechanism

VKM internal combustion engine

TS torsional vibration damper

AG differential gear

DW driving wheels

22 shaft

33 shaft

44 shaft

55 shaft

11 recess, oblong hole, bore hole

12 recess, oblong hole, bore hole

13 recess, oblong hole, bore hole

14 recess, oblong hole, bore hole

21 recess, oblong hole, bore hole

96 direction

97 direction

98 direction

99 direction

A1 actuator

A2 actuator

S1 actuating element, control rod

S2 actuating element, control rod

The invention claimed is:
 1. A transmission (G) for a motor vehicle,comprising: an electric machine (EM1); a first input shaft (GW1); asecond input shaft (GW2); an output shaft (GWA); a first planetary gearset (P1) and a second planetary gear set (P2), the first and secondplanetary gear sets (P1, P2) each comprising a first element (E11, E12),a second element (E21, E22), and a third element (E31, E32); and a firstshift element (A), a second shift element (B), a third shift element(C), a fourth shift element (D), and a fifth shift element (E), whereina rotor (R1) of the electric machine (EM1) is connected to the secondinput shaft (GW2), wherein the output shaft (GWA) is rotationally fixedto the second element (E22) of the second planetary gear set (P2), isrotationally fixable to the first input shaft (GW1) with the secondshift element (B), and is connectable to the third element (E31) of thefirst planetary gear set (P1) with the fifth shift element (E), whereinthe first element (E11) of the first planetary gear set (P1) is fixed toa rotationally fixed component (GG), wherein the first element (E12) ofthe second planetary gear set (P2) is fixable to the rotationally fixedcomponent (GG) with the first shift element (A), the second input shaft(GW2) is rotationally fixed to the second element (E21) of the firstplanetary gear set (P1) as well as to the third element (E32) of thesecond planetary gear set (P2), and wherein the first input shaft (GW1)is rotationally fixable to the second element (E21) of the firstplanetary gear set (P1) with the third shift element (C) and isrotationally fixable to the third element (E31) of the first planetarygear set (P1) with the fourth shift element (D).
 2. The transmission (G)of claim 1, wherein selective actuation of the first, second, third,fourth, and fifth shift elements (A, B, C, D, E) implements: a firstgear (1) between the first input shaft (GW1) and the output shaft (GWA)by engaging the first shift element (A) and the fourth shift element(D); a second gear between the first input shaft (GW1) and the outputshaft (GWA) by engaging the first shift element (A) and the third shiftelement (C); a third gear between the first input shaft (GW1) and theoutput shaft (GWA) in a first variant (3.1) by engaging the first shiftelement (A) and the second shift element (B), in a second variant (3.2)by engaging the second shift element (B) and the fifth shift element(E), in a third variant (3.3) by engaging the fourth shift element (D)and the fifth shift element (E), in a fourth variant (3.4) by engagingthe second shift element (B) and the third shift element (C), in a fifthvariant (3.5) by engaging the second shift element (B) and the fourthshift element (D); and a fourth gear between the first input shaft (GW1)and the output shaft (GWA) by engaging the third shift element (C) andthe fifth shift element (E).
 3. The transmission (G) of claim 1,wherein: a first gear (E2) results between the second input shaft (GW2)and the output shaft (GWA) by engaging the first shift element (A); anda second gear (E4) results between the second input shaft (GW2) and theoutput shaft (GWA) by engaging the fifth shift element (E).
 4. Thetransmission (G) of claim 1, further comprising a sixth shift element(F) arranged and configured for selectively connecting the first element(E12) of the second planetary gear set (P2) to the first input shaft(GW1).
 5. The transmission (G) of claim 4, wherein selective engagementof the first, second, third, fourth, fifth, and sixth shift elements (A,B, C, D, E, F) implements a third gear between the first input shaft(GW1) and the output shaft (GWA) in a sixth variant (3.6) by engagingthe second shift element (B) and the sixth shift element (F), and in aseventh variant (3.7) by engaging the third shift element (C) and thesixth shift element (F).
 6. The transmission (G) of claim 4, wherein:the third shift element (C) and the sixth shift element (F) are combinedto form a shift element pair (SP3); an actuating element is associatedwith the shift element pair (SP3); and the shift element pair (SP3) isconfigured such that either the third shift element (C) or the sixthshift element (F) is engageable by the actuating element from a neutralposition of the actuating element.
 7. The transmission (G) of claim 1,further comprising a seventh shift element (K) arranged and configuredfor selectively interlocking the second planetary gear set (P2).
 8. Thetransmission (G) of claim 7, wherein a third gear (E3) results betweenthe second input shaft (GW2) and the output shaft (GWA) by engaging theseventh shift element (K).
 9. The transmission (G) of claim 1, furthercomprising a further electric machine (EM2), a rotor (R2) of the furtherelectric machine (EM2) connected at the first input shaft (GW1).
 10. Thetransmission (G) of claim 1, further comprising an eighth shift element(K0), the first input shaft (GW1) is rotationally fixable to aconnection shaft (AN) with the eighth shift element (K0).
 11. Thetransmission (G) of claim 1, wherein one or more of the first, second,third, fourth, and fifth shift elements (A, B, C, D, E, F, K, K0) is aform-locking shift element.
 12. The transmission (G) of claim 1, whereinone or both of the first and second planetary gear sets (P1, P2) is aminus planetary gear set, wherein the first element (E11, E12) of eachminus planetary gear set is a respective sun gear, the second element(E21, E22) of each minus planetary gear set is a respective planetcarrier, and the third element (E31, E32) of each minus planetary gearset is a respective ring gear.
 13. The transmission (G) of claim 1,wherein: the second shift element (B) and the third shift element (C)are combined to form a shift element pair (SP2); an actuating element isassociated with the shift element pair (SP2); and the shift element pair(SP2) is configured such that either the second shift element (B) or thethird shift element (C) is engageable by the actuating element from aneutral position of the actuating element.
 14. The transmission (G) ofclaim 1, wherein: the second shift element (B) and the fourth shiftelement (D) are combined to form a shift element pair (SP2); anactuating element is associated with the shift element pair (SP2); andthe shift element pair (SP2) is configured such that either the secondshift element (B) or the fourth shift element (D) is engageable by theactuating element from a neutral position of the actuating element. 15.The transmission (G) of claim 1, wherein the rotor (R1) of the electricmachine (EM1) is rotationally fixed to the second input shaft (GW2) oris connected to the second input shaft (GW2) with at least one gearstage.
 16. A motor vehicle drive train for a hybrid or electric vehicle,comprising the transmission (G) of claim
 1. 17. A method for operatingthe transmission (G) of claim 1, wherein only the third shift element(C) is engaged in order to implement a charging operation or a startingoperation.